I don't work there, but I took a look at the source code and it appears that the dialog originates from here: https://github.com/PrimalHQ/primal-web-app/blob/870666becfa9e0e3adf0d7322e2ad788c799f3f1/src/contexts/AccountContext.tsx#L1049-L1055

Judging from the if-clause a few lines earlier, it does indeed check whether your updated follower list only has one account on it, and will display this dialog if it does. As to why that might happen, my best guess would be that the relay somehow returned an empty follow list.

Not sure what the best way to fix it is, since apparently this DOES sometimes happen. Perhaps a less confusing message and different options would be helpful. I'm thinking something along the lines of "Something went wrong fetching your follower list" with the options of "Try again" and "Cancel".